This invention is directed generally to ionography and electrophotography, and more specifically is directed to electroreceptors and photoreceptors which can provide different preferred dimensional characteristics for latent image-forming and for subsequent developing of the latent images.
Numerous different members have been proposed for imaging processes. These members include electrophotographic image forming members used in electrophotography and electroreceptors used in ionography. In electrophotography, an electrophotographic plate containing a photoconductive insulating layer on a conductive layer is imaged by first uniformly electrostatically charging its surface. The plate is then exposed to a pattern of activating electromagnetic radiation such as light. The radiation selectively dissipates the charge in the illuminated areas of the photoconductive insulating layer while leaving behind an electrostatic latent image in the non-illuminated areas. This electrostatic latent image may then be developed to form a visible image by depositing finely divided electroscopic marking particles on the surface of the photoconductive insulating layer. The resulting visible image may then be transferred from the electrophotographic plate to a support such as paper. This imaging process may be repeated many times with reusable photoconductive insulating layers.
In ionography, a latent image is created by writing on the surface of the imaging member with an ion head. The imaging member is preferably electrically insulating so that the charge applied by the ion head does not disappear prior to development. Therefore, ionographic receivers possess negligible, if any, photosensitivity. The absence of photosensitivity provides considerable advantages in ionographic applications. For example, the electroreceptor enclosure does not have to be completely impermeable to light and radiant fusing can be used without having to shield the receptor from stray radiation. Also, the level of dark decay in these ionographic receivers is characteristically low, thus providing a constant voltage profile on the receiver surface over extended time periods.
Electroreceptors are useful in ionographic imaging and printing systems such as those commercially available as the Xerox Corporation 4060 and 4075, which utilize an electrically resistive dielectric image receiver, i.e., an electroreceptor. In one simple form of the systems, latent images are formed by depositing ions in a prescribed pattern onto the electroreceptor surface with a linear array of ion emitting devices or ion heads, creating a latent electrostatic image. Charged toner particles are then passed over these latent images causing the toner particles to remain where a charge has previously been deposited. This developed image is sequentially transferred to a substrate such as paper, and permanently affixed thereto.